摆动液压缸圆环螺旋流的流动及内泄漏研究

考虑液压油的黏度随温度与压强的变化, 以连续性方程、N-S方程、能量方程为基础, 推导出螺旋摆动液压缸内部圆环螺旋流的速度方程及泄漏量方程. 运用大型通用CFD仿真软 件fluent对螺旋摆动液压缸内部的圆环螺旋流流场及泄漏规律进行数值仿真. 对螺旋摆 动液压缸内螺旋流动的理论计算与仿真结果进行对比分析, 结果表明理论推导正确, 从而为螺旋摆动 缸内泄漏及容积耗损提供理论依据.     

一种稳定的自由空间量子密钥分配实验系统

基于量子密钥分配的基本原理,采用B92方案,以单光子作为信息载体,使用极化编码,搭建了一个简单易行的实验装置,实现了自由空间传输的量子密钥分配,平均每脉冲光子数为0．1,粗码率12．7kbits／s,误码率4％左右。     

利用拉格朗日方程求解离子在分阱系统中的集体振动模式

介绍了利用拉格朗日方程求解离子在分阱系统中的集体振动模式的基本原理,并具体计算了分阱系统中3个离子的集体振动模式.     

气体分子平均相对运动速率的推导

从相对速度的定义和气体分子的速度分布律出发,分别得到了气体分子相对运动速度和速率的分布律,简洁的给出了平均相对运动速率和平均速率之间的关系.     

Quantum secret sharing based on quantum error-correcting codes

Quantum secret sharing(QSS) is a procedure of sharing classical information or quantum information by using quantum states.This paper presents how to use a [2k-1,1,k] quantum error-correcting code(QECC) to implement a quantum(k,2k 1) threshold scheme.It also takes advantage of classical enhancement of the [2k-1,1,k] QECC to establish a QSS scheme which can share classical information and quantum information simultaneously.Because information is encoded into QECC,these schemes can prevent intercept-resend attacks and be implemented on some noisy channels.     

Polarization Encoded Quantum Key Distribution over Special Optical Fibres

Employing a polarization compensator, an optical fibre quantum key distribution （QKD） system based on polarization coding has been developed. To obtain the compensator setting parameters, the measurement of the laser pulse polarization is performed with one single photon detector. We obtain a sifted key bit rate of about 2kbits/s and a qubit error rate lower than 10% within 3.5h. It is shown that polarization coding can be used for QKD over optical fibres as well. At the same time, the system is simple, easy to operate, practical and user-friendly. It gains more advantages than other systems over optical fibres when used in local area quantum communications and where the functional agility is important.     

Quantum Secret Sharing with Two-Particle Entangled States

We present a new protocol for the quantum secret sharing （QSS） task among multiparties with two-particle entangled states. In our scheme, the secret is split among a number of participatlng partners and the reconstruction requires collaboration of all the authorized partners. Instead of multiparticle Greenberger-Horne-Zeillnger states, only two-particle entangled states are employed in this scheme. By local operations and individual measurements on either of the two entangled particles, each authorized partner obtains a sequence of secret bits shared with other authorized partners. This protocol can be experimentally realized using only linear optical elements and simple entanglement source. It is scalable in practice.     

Scalable Quantum Secret Sharing Extended from Quantum Key Distribution

We suggest a general approach for extending quantum key distribution （Q, KD） protocols possessing discrete rotational symmetry into quantum secret sharing （QSS） schemes among multiparty, under certain conditions. Only local unitary operations are required for this generalization based on the almost mature technologies of Q, KD. Theoretically, the number of the participating partners can be arbitrary high. As an application of this method, we propose a fault-tolerant QSS protocol based on a fault-tolerant QKD implementation. The 6-state protocol is also discussed.     

薄板坯连铸结晶器中铸坯凝固壳应力发展的有限元分析

对薄板坯连铸结晶中铸坯凝固壳应力的发展过程建立了有限元分析模型。在计算铸坯温度场和凝壳厚度分布的基础上用热弹粘性模型数值模拟了凝固壳中的应力发展过程，同时得到了凝壳断面从结晶器液池顶面到结晶器出口处的移支过程中各部位裂纹产生倾向的大小。模型中考虑了钢水静压力的作用和结晶器锥度，计算结果合理。     

近岸4种鱼的声散射特征提取及融合实验研究*

为了有效地提取表征鱼类间差异的声散射特征参数,该文通过绳系法实验研究了近岸4种经济鱼类的声散射信号特征提取及融合方法。首先,通过自研双频鱼探仪采集花鲈、许氏平鲉、黑鲷和斑石鲷的个体鱼声散射信号;然后,分别测定200 kHz和450 kHz换能器下鱼体的目标强度,同时提取鱼声散射信号的时频域统计特征;最后,将降维后的时频特征与频差特征融合组成新的特征向量。该文通过实验验证了该方法的有效性,基于组合特征的支持向量机识别准确率达93%。结果表明,鱼的频率响应特性和鱼声散射信号的时频域统计特征能一定程度上反映鱼的固有属性,有效地增加判别依据能显著提高以上4种鱼类的识别准确率。